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Magnetic field effects

J Sonntag, S Reichardt, L Wirtz, B Beschoten, M I Katsnelson, F Libisch, C Stampfer
We present magneto-Raman spectroscopy measurements on suspended graphene to investigate the charge carrier density-dependent electron-electron interaction in the presence of Landau levels. Utilizing gate-tunable magnetophonon resonances, we extract the charge carrier density dependence of the Landau level transition energies and the associated effective Fermi velocity v_{F}. In contrast to the logarithmic divergence of v_{F} at zero magnetic field, we find a piecewise linear scaling of v_{F} as a function of the charge carrier density, due to a magnetic-field-induced suppression of the long-range Coulomb interaction...
May 4, 2018: Physical Review Letters
Zheng-Xin Liu, B Normand
Motivated by recent experimental observations in α-RuCl_{3}, we study the K-Γ model on the honeycomb lattice in an external magnetic field. By a slave-particle representation and variational Monte Carlo calculations, we reproduce the phase transition from zigzag magnetic order to a field-induced disordered phase. The nature of this state depends crucially on the field orientation. For particular field directions in the honeycomb plane, we find a gapless Dirac spin liquid, in agreement with recent experiments on α-RuCl_{3}...
May 4, 2018: Physical Review Letters
Vassilis Tangoulis, Nikolia Lalioti, John Parthenios, Nikos Boukos, Ondřej Malina, Jiří Tuček, Radek Zbořil
While synthetic methods for the grafting of nanoparticles or photoactive molecules onto carbon nanotubes (CNTs) have been developed in the last years, a very limited number of reports have appeared on the grafting of single-molecule magnets (SMMs) onto CNTs. There are many potential causes, mainly focused on the fact that the attachment of molecules on surfaces remains not trivial and their magnetic properties are significantly affected upon attachment. Nevertheless, implementation of this particular type of hybrid material in demanding fields such as spintronic devices makes of utmost importance the investigation of new synthetic protocols for effective grafting...
May 18, 2018: Inorganic Chemistry
Alexander Tejani, Qais Naziri, Preston W Grieco, Robert Pivec, Damon Greene, Bhaveen V Kapadia, Dipal Chatterjee, William P Urban
Prior studies have not found significant differences in meniscal parameters between patients with meniscal and ligamentous injury and those without. The purpose of this study was to determine whether such relationships exist. Clinical records and magnetic resonance images of three subject groups were reviewed. Group 1 solely had meniscal tears (medial/lateral), Group 2 had meniscal tears with concurrent ACL tears, and Group 3 had healthy knees. The mean age of subjects included was 35.9 years (range 8.2-72...
2018: Journal of Long-term Effects of Medical Implants
Natalia V Bobkova, Vadim V Novikov, Natalia I Medvinskaya, Irina Y Aleksandrova, Inna V Nesterova, Eugenii E Fesenko
Subchronic effect of a weak combined magnetic field (MF), produced by superimposing a constant component, 42 µT and an alternating MF of 0.08 µT, which was the sum of two frequencies of 4.38 and 4.88 Hz, was studied in olfactory bulbectomized (OBE) and transgenic Tg (APPswe, PSEN1) mice, which were used as animal models of sporadic and heritable Alzheimer's disease (AD) accordingly. Spatial memory was tested in a Morris water maze on the following day after completion of training trials with the hidden platform removed...
May 17, 2018: Electromagnetic Biology and Medicine
Ryo Nitta, Tsuyoshi Imasaki, Eriko Nitta
The recent 'resolution revolution' in structural analyses of cryo-electron microscopy (cryo-EM) has drastically changed the research strategy for structural biology. In addition to X-ray crystallography and nuclear magnetic resonance spectroscopy, cryo-EM has achieved the structural analysis of biological molecules at near-atomic resolution, resulting in the Nobel Prize in Chemistry 2017. The effect of this revolution has spread within the biology and medical science fields affecting everything from basic research to pharmaceutical development by visualizing atomic structure...
May 16, 2018: Microscopy
Ritwik Mondal, Marco Berritta, Peter Oppeneer
The phenomenological Landau-Lifshitz-Gilbert (LLG) equation of motion remains as the cornerstone of contemporary magnetisation dynamics studies, wherein the Gilbert damping parameter has been attributed to first-order relativistic effects. To include magnetic inertial effects the LLG equation has previously been extended with a supplemental inertia term and the arising inertial dynamics has been related to second-order relativistic effects. Here we start from the relativistic Dirac equation and, performing a Foldy-Wouthuysen transformation, derive a generalised Pauli spin Hamiltonian that contains relativistic correction terms to any higher order...
May 17, 2018: Journal of Physics. Condensed Matter: An Institute of Physics Journal
Jiaen Liu, Jacco A de Zwart, Peter van Gelderen, Joseph Murphy-Boesch, Jeff H Duyn
PURPOSE: To identify and characterize the sources of B0 field changes due to head motion, to reduce motion sensitivity in human brain MRI. METHODS: B0 fields were measured in 5 healthy human volunteers at various head poses. After measurement of the total field, the field originating from the subject was calculated by subtracting the external field generated by the magnet and shims. A subject-specific susceptibility model was created to quantify the contribution of the head and torso...
May 16, 2018: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
Han Hu, Tzu-Chien Lin, Tsan-Chuen Leung, Wan-Sheng Su
The field screening effect on the electronic and field-emission properties of zigzag graphene nanoribbons (ZGNRs) has been studied using first-principles calculations. We have systematically investigated the effects of inter-ribbon distance and ribbon width on the work function, field enhancement factor, band gap and edge magnetism of zigzag graphene nanoribbons (ZGNRs). It is found that the work function of ZGNRs increases rapidly as the inter-ribbon distance Dx increases, which is caused by the positive dipole at the edge of the ribbon...
May 17, 2018: Physical Chemistry Chemical Physics: PCCP
Ping-Ching Wu, Dar-Bin Shieh, Hung-Tsung Hsiao, Jeffery Chi-Fei Wang, Ya-Chi Lin, Yen-Chin Liu
BACKGROUND: Nanoparticles have become one of the most promising among the potential materials used for biomedical applications. However, few researchers have focused on their effects on analgesia. Despite the fact that various nanoparticles have been evaluated for drug delivery and MRI imaging contrast enhancement in clinical settings, no reports have investigated the in vivo synergy of ketorolac iron-oxide nanoparticle conjugates to improve the analgesic effect. METHODS: Ketorolac conjugated magnetic iron oxide nanoparticles (Keto-SPIO) were synthesized via two-stage additions of protective agents and chemical co-precipitation...
May 16, 2018: Journal of Nanobiotechnology
Zuocheng Dai, Yan Huang, Huan Yang, Pingping Yao, Yuxiang Yang, Chaoying Ni
Magnetic fluids (MFs) with good dispersion were prepared by speed-controlled co-precipitation method, using polyethylene glycol (PEG-4000) as dispersing agent. To functionalize the MFs with graphene oxide (GO), highly dispersed nano-magnetic particles (NMPs) were firstly prepared by low-temperature freeze-drying technique. 3-aminopropyltriethoxysilane (APTES) was then attached on the surface of NMPs to form amino functionalized NMPs. GO was finally assembled with amino functionalized NMPs, to prepare GO functionalized MFs (GO-NMPs) by electrostatic adsorption...
January 1, 2018: Journal of Nanoscience and Nanotechnology
Xin Wen, Huanhuan Zhang, Fei Tian, Xiaofang Liu, Libo Niu, Guoyi Bai
A novel H3PW12O40 deposited chitosan coated iron oxide magnetic core-shell nanocomposite (Fe3O4@CS@HPW) was prepared via a facile approach. Fe3O4 nanoparticles were first coated with crosslinking-agent-free chitosan, and then H3PW12O40 was loaded onto the surface of chitosan as an outer shell. The resultant nanocomposite was well characterized by Brunauer-Emmett-Teller surface area analysis (BET), inductively coupled plasma analysis (ICP), X-ray diffraction (XRD), fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM) and elemental mappings...
January 1, 2018: Journal of Nanoscience and Nanotechnology
Yuanna Zhu, Jianrong Wang, Yingzi Wang, Xueling Song, Yanan Xu, Ping Yang
Fe3O4@AlOOH adsorbent with high efficient adsorption capacity was successfully synthesized by controlling the hydrolysis rate for aluminum isopropoxide (AIP) and introducing inductive agent thioglycolic acid (TGA). Al(OH)3-TGA clusters played a key role in the formation of Fe3O4@AlOOH adsorbent with lamellar structure. Morphology characterization revealed that magnetic Fe3O4 nanoparticles were uniformly deposited on the surface of AlOOH. The lamellar structure of AlOOH and the strong magnetic intensity of Fe3O4 were helpful for its rapid separation from solution under external magnetic field...
January 1, 2018: Journal of Nanoscience and Nanotechnology
Yanping Miao, Ping Yang
The α-Fe2O3/graphene composites were obtained by solvothermal method, graphene oxide (GO) nanosheets were served as supporting materials for anchoring the α-Fe2O3, GO was reduced during this process. The morphology and structure of composites were characterized by X-ray powder diffraction, Scanning electron microscope and Transmission electron microscopy. Compared with the bare α-Fe2O3 nanoplates, the morphology of α-Fe2O3 decorated in graphene partly changed from nanoplates to truncate octahedral. Because of the synergistic effect of graphene and α-Fe2O3, the α-Fe2O3/graphene composites exhibited improved photocatalytic performance, significantly better than that of the bare α-Fe2O3 nanoplates...
January 1, 2018: Journal of Nanoscience and Nanotechnology
Santiago Rodríguez-Jiménez, Alexis S Barltrop, Nicholas G White, Humphrey L C Feltham, Sally Brooker
Two isomeric pyrimidine-based Rdpt-type triazole ligands were made: 4-(4-methylphenyl)-3-(2-pyrimidyl)-5-phenyl-4 H-1,2,4-triazole (L2pyrimidine ) and 4-(4-methylphenyl)-3-(4-pyrimidyl)-5-phenyl-4 H-1,2,4-triazole (L4pyrimidine ). When reacted with [FeII (pyridine)4 (NCE)2 ], where E = S, Se, or BH3 , two families of mononuclear iron(II) complexes are obtained, including six solvatomorphs, giving a total of 12 compounds: [FeII (L2pyrimidine )2 (NCS)2 ] (1), [FeII (L2pyrimidine )2 (NCSe)2 ] (2), 2·1.5H2 O, [FeII (L2pyrimidine )2 (NCBH3 )2 ]·2CHCl3 (3·2CHCl3 ), 3 and 3·2H2 O, [FeII (L4pyrimidine )2 (NCS)2 ] (4), 4·H2 O, [FeII (L4pyrimidine )2 (NCSe)2 ] (5), 5·2CH3 OH, 5·1...
May 16, 2018: Inorganic Chemistry
Alexander A Kopasov, Ivan M Khaymovich, Alexander S Mel'nikov
We study the influence of the inverse proximity effect on the superconductivity nucleation in hybrid structures consisting of semiconducting nanowires placed in contact with a thin superconducting film and discuss the resulting restrictions on the operation of Majorana-based devices. A strong paramagnetic effect for electrons entering the semiconductor together with spin-orbit coupling and van Hove singularities in the electronic density of states in the wire are responsible for the suppression of superconducting correlations in the low-field domain and for the reentrant superconductivity at high magnetic fields in the topologically nontrivial regime...
2018: Beilstein Journal of Nanotechnology
Daniel Hey, Enbang Li
Photons are weak particles that do not directly couple to magnetic fields. However, it is possible to generate a photonic gauge field by breaking reciprocity such that the phase of light depends on its direction of propagation. This non-reciprocal phase indicates the presence of an effective magnetic field for the light itself. By suitable tailoring of this phase, it is possible to demonstrate quantum effects typically associated with electrons, and, as has been recently shown, non-trivial topological properties of light...
April 2018: Royal Society Open Science
Susanne Mayer-Wagner, Florian Hammerschmid, Helmut Blum, Stefan Krebs, Julia I Redeker, Boris M Holzapfel, Volkmar Jansson, Peter E Müller
Introduction: Low frequency electromagnetic fields (LF-EMF) and simulated microgravity (SMG) have been observed to affect chondrogenesis. A controlled bioreactor system was developed to apply LF-EMF and SMG singly or combined during chondrogenic differentiation of human mesenchymal stem cells (hMSCs) in 3D culture. Material and methods: An external motor gear SMG bioreactor was combined with magnetic Helmholtz coils for EMF (5 mT; 15 Hz). Pellets of hMSCs (±TGF-β3) were cultured (P5) under SMG, LF-EMF, LF-EMF/SMG and control (1 g) conditions for 3 weeks...
April 2018: Archives of Medical Science: AMS
Sangita Sen, Erik I Tellgren
External non-uniform magnetic fields acting on molecules induce non-collinear spin densities and spin-symmetry breaking. This necessitates a general two-component Pauli spinor representation. In this paper, we report the implementation of a general Hartree-Fock method, without any spin constraints, for non-perturbative calculations with finite non-uniform fields. London atomic orbitals are used to ensure faster basis convergence as well as invariance under constant gauge shifts of the magnetic vector potential...
May 14, 2018: Journal of Chemical Physics
Sonja M Schellhammer, Sebastian Gantz, Armin Lühr, Bradley M Oborn, Michael Bussmann, Aswin L Hoffmann
PURPOSE: Given its sensitivity to anatomical variations, proton therapy is expected to benefit greatly from integration with magnetic resonance imaging for on-line anatomy monitoring during irradiation. Such an integration raises several challenges, as both systems mutually interact. The proton beam will experience quasi-continuous energy loss and energy-dependent electromagnetic deflection at the same time, giving rise to a deflected beam trajectory and an altered dose distribution with a displaced Bragg peak...
May 15, 2018: Medical Physics
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